The neurosurgeon is frequently confronted with the necessity of repairing dural defects due to trauma, tumor resection, and decompressive procedures. Numerous materials have been investigated for use in the repair of the dura mater and underlying tissues. Current options include autologous materials (e.g. pericranium, temporalis fascia, and tensor fascia lata), lyophilized cadaveric materials (e.g. dura mater and tensor fascia lata) and synthetic materials (e.g. Silastic sheets, Dacron sheets, Vicryl mesh); however, each of these materials is associated with significant limitations.
One object of the present invention is to provide a biodegradable material that can serve as a dural substitute.
Many individuals have suffered injuries to their central nervous system that leave the individual partially paralyzed or result in reduced motor function. Repair strategies and graft material for repairing damage to the central nervous system do not currently exist. In particular nerve fibers within the brain and the spinal cord, which differ structurally from peripheral nerves, will not regenerate after they have been severed or crushed. For example there is no currently known treatment for humans that promotes functional regeneration across a complete spinal cord transection or a severed optic nerve.
An additional object of the present invention is to provide a composition and method that promotes the production of endogenous central nerve cells thus allowing the repair of damage to both central nervous system tissues and peripheral nerve tissues.
It is known that compositions comprising the tunica submucosa delaminated from both the tunica muscularis and at least the luminal portion of the tunica mucosa of the intestine of warm-blooded vertebrates can be used as tissue graft materials. See, for example, U.S. Pat. Nos. 4,902,508 and 5,281,422. The compositions described in those patents are characterized by excellent mechanical properties, including high compliance, a high burst pressure point, and an effective porosity index which allowed such compositions to be used beneficially for vascular graft constructs and in connective tissue replacement applications. When used in such applications the submucosal graft constructs appear to serve as a matrix for the regrowth of the tissues replaced by the graft constructs. Furthermore, as described in U.S. Pat. No. 5,275,826 fluidized forms of vertebrate submucosal tissues can also be used as injectable or implantable tissue grafts without loss of biotropic properties. Significantly, too, in over 600 cross-species implants, submucosa-derived graft compositions have never been shown to elucidate a tissue graft rejection reaction.
Applicants have discovered that submucosal tissue induces the growth and proliferation of neurological related tissues, including the dura mater and nerve cells of the central and peripheral nervous system. Accordingly, the present invention is directed to the use of submucosal tissue as a graft construct for promoting the repair of damaged or diseased neurological related tissues.